Neltnerite

General Information:
 Chemical Formula:
CaMn+++6SiO12
 Composition:
(Molecular Weight = 589.78 gm)
Calcium 6.80 % Ca
Manganese 55.89 % Mn
Silicon 4.76 % Si
Oxygen 32.55 % O 
 Empirical Formula:
CaMn3+6SiO12
 IMA Status:
Approved IMA 1979
Physical Properties:
 Cleavage:
[???] Indistinct
 Color:
black.
 Density:
4.63
 Diaphaniety:
Opaque
 Hardness:
6 - Orthoclase
 Luster:
Sub Metallic
 Streak:
black
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